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Updated: Jul 10 2017

Transient Ischemic Attack

Snapshot
  • 55-year-old woman with history of hypertension and hyperlipidemia, presents with sudden onset slurred speech at noon time while eating with friends, immediately brought to ED within the hour, where her symptom spontaneously resolved. DWI sequence on MRI unrevealing for acute stroke. However, multiple punctate hypodensities isodense to CSF present on CT indicating old infarcts.
Introduction
  • Definition: 
    • "A transient episode of neurologic dysfuction caused by focal brain, spinal cord, or retina ischemia, without acute infarction"
      • this is the latest revised definition endorsed by AHA/ASA
      • note the 24hr time window in the previous defintion is no longer present
      • unclear currently how to classify transient symtoms with infarction on imaging 
    • increased risk of future stroke
Epidemiology
  • Incidence: 200,000 to 300,000
  • Men > women
  • African american > caucasian
  • Significant stroke risk:
    • 5% will have stroke in first 48 hours
    • 10% will have stroke in 90 days
    • 30-40% will have ischemic stroke in 3-5 years
    • TIA in patients with carotid stenosis have highest stroke risk
      • 20% in 3 months
Evaluation
  • History
    • usually sudden onset
    • progressive onset of symptoms suggests alternative diagnosis
    •  weakness, paresis, sensation loss, aphasia, dysarthria
      • symptoms typically involve loss, sudden decline in function
    • tremors, abnormal movements, dysthesias, flashing lights and other positive symptoms very atypical
    • Pain is also very atypical
  • Physical
    • classically should be focal, and localizable to vascular territory
    • exam should be no different than for stroke
      • full neurologic exam
      • neck exam for carotid bruits
      • cardiac exam for murmurs
  • ECG
    • 3% of TIA patients have new atrial fibrillation
  • Telemetry
    • 24hr telemetry typically in patient
      • unclear of additional benefit
    • Extended telemetry or Holter monitor more helpful
      • can reveal paroxysmal afib in 14% of TIA patients
  • TTE/TEE
    • helpful in patients with cardiac history
      • can reveal a possible cardioembolic source in 46% of patient
    • unhelpful in patients without cardiac history
      • TTE only reveals possible cardioembolic source in up to 3% of patients
  • Laboratory 
    • coagulation studies are currently recommended by ASA/AHA
      • yield is low
    • vascular risk stratification labs 
      • lipid panel 
      • hemoglobin a1c
Imaging
  • Brain imaging 
    • all patients should have emergent imaging within 24hrs to rule out infarct
    • MRI prefered
      • DWI sequence extremely sensitive for edema
        • not all DWI lesions indicate infarction
    • CT most frequently used due to availability
      • variable sensitivity: 4-34%
  • Vascular Imaging
    • Important for risk stratification and preventative management
    • CT Angiography
      • very reliable for carotid stenosis, cervical dissection
    • Transcranial Doppler with color
      • can exclude intracranial stenosis with a negative predictive value up to 86%
    • Ultrasound of the neck 
      • to search for carotid plaques
    • MRA with contrast
      • useful for imaging supra-aortic but extracranial vessels
      • sensitivity and specitivity in the 90% range
Risk Stratification
  • ABCD2 score
    • estimates stroke after TIA
    • 0-3 points = 3.1% 90 day stroke risk
    • 4-5 points = 9.8% 90 day stroke risk
    • 6-7 points = 17.8% 90 day stroke risk
Management
  • Position patient supine if possible
    • Can increase cerebral perfusion by 20% with 30 degree incline
  • Withold anti-hypertensives unless BP>220/120
    • AHA/ASA concensus panel recommendation
    • can restart antihypertensives if patient stable after the first 24 hours
  • Initiate anti-platelet
    • All patients should be aspirin loaded
    • Aggrenox superior to aspirin but similar benefit to plavix
    • Plavix in patients intolerant of aspirin
  • If cervical carotid dissection, patient will require 3-6 months antithrombotic therapy
    • unclear if anticoagulation or antiplatelet superior
  • Thrombolysis in TIA is contraindicated
  • Consider carotid endarterectomy in patients with >70% carotid stenosis
    • for patients >70, can reduce stroke risk by 15%
  • Lipid panel with goal LDL<70 
  • Encourge life style modification
    • physical activity can reduce stroke risk by 20%
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